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Species · BCR 12 · BBS 2025 Release · 1966–2024

Swainson's Thrush In Boreal Hardwood Transition

All regionsBoreal Hardwood TransitionForest birds

Swainson's Thrush in Boreal Hardwood Transition has surged: up 190% on the route-weighted index since 1969.

+190%Since 1969TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
76Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Swainson's Thrush has surged in Boreal Hardwood Transition: up 190% on the route-weighted index since 1969.

Swainson's Thrush In Boreal Hardwood Transition Population Forecast

If the recent trend holds, Swainson's Thrush in Boreal Hardwood Transition is projected to rise about 72% by 2029 — from 0.75 in 2024 to a central estimate of 1.3 (95% range 0.77–1.8). A 5-year backtest shows a typical error of ±23.1%, with 100% of held-out values landing inside the 95% band.

+72%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
1.3Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.77–1.895% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±23.1%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Swainson's Thrush in Boreal Hardwood Transition is projected to rise about 72% by 2029 — from 0.75 in 2024 to a central estimate of 1.3 (95% range 0.77–1.8). A 5-year backtest shows a typical error of ±23.1%, with 100% of held-out values landing inside the 95% band.19672029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20251.20.711.7
20261.20.731.8
20271.30.741.8
20281.30.751.8
20291.30.771.8

Routes In Boreal Hardwood Transition

Routes recording Swainson's Thrush in Boreal Hardwood Transition.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Sawbill CampMINNESOTA282024
JordanMINNESOTA132023
HovlandMINNESOTA92024
Big Island LakeMICHIGAN82010
Brush CreekMICHIGAN61983
Cluster LakesMICHIGAN62010
Sawbill LndgMINNESOTA42024
DebsMINNESOTA42012
HermanMICHIGAN32022
Gibbs CityMICHIGAN32024
ShingletonMICHIGAN32024
Betchler LksMICHIGAN32016
Cass LakeMINNESOTA31995
Union TwpWISCONSIN31993
OntonagonMICHIGAN22019
Brocky LakeMICHIGAN21995
MuskallongeMICHIGAN22023
TahquamenonMICHIGAN22024
Imp LakeMICHIGAN22018
Hiawatha NfMICHIGAN22024
SidnawMICHIGAN22024
Scott'S MarshMICHIGAN22010
GooseneckMICHIGAN22010
CromwellMINNESOTA22004
Mille LacsMINNESOTA21998

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.